粲偶素双光子衰变的格点QCD研究  

First-principle calculation of theη_(c)→2γdecay width from lattice QCD

作　　者：孟雨 冯旭 刘川 王腾 邹作恒 Yu Meng;Xu Feng;Chuan Liu;Teng Wang;Zuoheng Zou(School of Physics and Microelectronics,Zhengzhou University,Zhengzhou 450001,China;School of Physics,Peking University,Beijing 100871,China;Center for High Energy Physics,Peking University,Beijing 100871,China;Collaborative Innovation Center of Quantum Matter,Beijing 100871,China;State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China)

机构地区：[1]School of Physics and Microelectronics,Zhengzhou University,Zhengzhou 450001,China [2]School of Physics,Peking University,Beijing 100871,China [3]Center for High Energy Physics,Peking University,Beijing 100871,China [4]Collaborative Innovation Center of Quantum Matter,Beijing 100871,China [5]State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China

出　　处：《Science Bulletin》2023年第17期1880-1885,共6页科学通报（英文版）

基　　金：the support by the National Natural Science Foundation of China(12047505);State Key Laboratory of Nuclear Physics and Technology,Peking University;supported in part by the National Natural Science Foundation of China(12125501,12141501,and 11775002);National Key Research and Development Program of China(2020YFA0406400);supported in part by the National Natural Science Foundation of China(12070131001);supported in part by Chinese Academy of Sciences Interdisciplinary Innovation Team and the National Natural Science Foundation of China(11935017,12293060,and 12293063);partly supported by Highperformance Computing Platform of Peking University。

摘　　要：粲偶素的双光子衰变过程,无论是实验测量还是理论研究,一直以来都存在诸多困难.不同的理论研究给出的结论迥异,而已有的实验测量精度又非常有限,无法精确检验相关的理论研究.本文采用第一性原理计算的格点QCD方法,借助提出的新的格点研究方案,在综合考虑了各种系统误差之后,给出了精度为2.6%的理论计算结果.该结果与PDG数值相差2.9倍标准差,背后的原因需要更为深入的探索.因此,未来更加精确的实验测量、相关的理论研究以及其他格点研究团队的进一步检验将发挥重要的作用.We perform a lattice QCD calculation of theη_(c)→2γdecay width using a model-independent method that requires no momentum extrapolation of the off-shell form factors.This method also provides a straightforward and simple way to examine the finite-volume effects.The calculation is accomplished using N_(f)=2 twisted mass fermion ensembles.The statistically significant excited-state effects are observed and eliminated using a multi-state fit.The impact of fine-tuning the charm quark mass is also examined and confirmed to be well-controlled.Finally,using three lattice spacings for the continuum extrapolation,we obtain the decay widthГη_(cγγ)=6:67(16)_(stat)(6)_(syst)keV,which differs significantly from the Particle Data Group’s reported value ofГη_(cγγ)5:4(4)keV(2.9σ tension).We provide insight into the comparison between our findings,previous theoretical predictions,and experimental measurements.

关 键 词：格点QCD 双光子 精确检验 粲偶素 第一性原理计算 衰变过程 系统误差 标准差 

分 类 号：O572.243[理学—粒子物理与原子核物理]